The present invention relates to a vibration-canceling mechanism for an object subjected to a mechanical vibration, and to a head gimbal assembly (HGA) with the vibration-canceling mechanism.
In a magnetic disk drive apparatus, thin-film magnetic head elements for writing magnetic information into and/or reading magnetic information from magnetic disks are in general formed on magnetic head sliders flying in operation above the rotating magnetic disks. The sliders are supported at top end sections of suspensions of HGAs, respectively.
In operation, the HGA and therefore the magnetic head slider are driven or swung along a radial direction of the magnetic disk (track-width direction) by an actuator called as a voice coil motor (VCM), and thus a position of the magnetic head element with respect to a track in the magnetic disk is controlled.
The actuator, a drive arm coupled to the actuator and a suspension have inherent resonance characteristics with resonance frequencies different from each other, respectively. Thus, to the magnetic head slider attached at the top end section of the suspension, a mechanical vibration modified by a composite characteristic of these inherent resonance characteristics will be transferred.
In order to suppress such mechanical vibration modified by the composite resonance characteristic, conventionally, a resonance peak of an electrical drive signal was suppressed by at least one multi-stage filter mounted in a servo circuit of the actuator.
However, because such electrical vibration-suppressing method needed to provide the multi-stage filter, the servo circuit was complicated in configuration and thus the manufacturing cost increased. Also, since the mechanical vibration was suppressed by the electrical means not directly by a mechanical means an efficiency for suppression was extremely low.
There has been no mechanism for mechanically and simultaneously suppressing vibrations due to a plurality of resonance frequencies of a vibration-origination system consisting of a suspension, an actuator and a drive arm for example.
It is therefore an aim of the present invention to provide a vibration-canceling mechanism and an HGA with the vibration canceling, whereby a mechanical vibration applied to an object can be suppressed with efficiency without greatly changing a conventional structure of the HGA.
Another aim of the present invention is to provide a vibration-canceling mechanism and an HGA with the vibration canceling, whereby vibrations due to a plurality of resonance frequencies of a vibration-origination system can be simultaneously suppressed.
Further aim of the present invention is to provide-a vibration-canceling mechanism and an HGA with the vibration canceling, whereby a configuration of a servo circuit of an actuator can be simplified.
According to the present invention, a vibration-canceling mechanism includes a vibration transfer member of a plane shape inserted between a vibration-origination system having a plurality of resonance frequencies and an object to which vibrations are applied from the vibration-origination system. The vibration transfer member has a plurality of resonance frequencies equal to or near the plurality of resonance frequencies of the vibration-origination system. The vibration transfer member has a plurality of pairs of arm sections for coupling one end section of the vibration transfer member with the other end section of the vibration transfer member. The one end section of the vibration transfer member is fixed to the vibration-origination system and the other end section of the vibration transfer member is fixed to the object so that apparent vibrations of the object are substantially canceled by resonances of the vibration transfer member.
When the vibration-origination system resonates at a plurality of resonance frequencies, the vibration transfer member also resonates at a plurality of resonance frequencies. The one end section of the vibration transfer member vibrates in phase with the vibration-origination system but the other end section of the vibration transfer member vibrates in substantially inverted phase or deviated phase as the vibration-origination system. Therefore, the vibration transfer member operates so as to move a position of the object back to its original position that will be positioned when no resonance occurs, resulting the apparent vibrations of the object to cancel.
As aforementioned, according to the present invention, only by additionally attaching the vibration transfer member with a simple structure, the mechanical vibrations can be extremely effectively canceled without greatly changing a conventional structure of the HGA. Also, since a configuration of a servo circuit of the actuator can be simplified, a manufacturing cost of the magnetic disk drive apparatus can be reduced.
Also, since the vibration transfer member is configured in a plane shape, no bending process is needed and its characteristics can be adjusted only by executing a photo-etching process. Thus, a fabrication of the vibration transfer member can become very easy and also extremely high precision can be expected. The latter will present the minimum variation in the characteristics caused by a dimensional error.
Particularly, according to the present invention, because the vibration transfer member has a plurality of pairs of arm sections for coupling one end section of the vibration transfer member with the other end section of the vibration transfer member so as to vibrates at a plurality of resonance frequencies that are equal to or near the plurality of resonance frequencies of the vibration-origination system, vibrations due to these plurality of resonance frequencies applied to the object can be simultaneously and effectively suppressed.
It is preferred that the vibration-canceling mechanism further includes first damper layers provided between the other end section of the vibration transfer member and the vibration-origination system, for attenuating the vibration of the object. To the both surfaces of the first damper layers, vibrations of substantially inverted phase or deviated phase with each other are applied from the vibration-origination system and the vibration transfer member, respectively. Thus the first damper layers operate to restrict an excessive inverse-movement of the vibration transfer member so as to attenuate the amplitude of the vibrations, and therefore the vibrations of the object fixed to the other end section of the vibration transfer member are attenuated.
It is also preferred that the vibration-canceling mechanism further includes a second damper layer provided between the one end section of the vibration transfer member and the object, for attenuating the vibration of the object.
Preferably, the first and/or second damper layers are formed by a flexible resin adhesive adhered to the vibration transfer member and to the vibration-origination system.
Also it is preferred that the vibration-canceling mechanism is configured to apply a load in an up-and-down direction to the first and/or second damper layers. By applying the load, the damping effect of the damping layers win increase. The resonance frequency of a system consisting of the vibration transfer member and the damper layers varies depending upon a level of the applied load.
It is preferred that the vibration-origination system is a support member including a suspension, and that the object is a head slider with at least one head element attached to a top end section of the suspension.
It is further preferred that the head slider is fixed to one surface of the vibration transfer member and the suspension is fixed to the other surface of the vibration transfer member. Since the first damper layers are provided between the other end section of the vibration transfer member and the suspension, a gap space for inserting an adhesive can be automatically obtained between the vibration transfer member and the suspension. This results extremely easy assembling of the vibration transfer member with the suspension. Also, if the second damper layer is provided between the one end section of the vibration transfer member and the head slider, a gap space for inserting an adhesive can be automatically obtained between the vibration transfer member and the head slider. This results extremely easy assembling of the vibration transfer member with the head slider.
It is preferred that the head slider has a surface opposite to its air bearing surface (ABS), and that the vibration transfer member consists of a plane metal plate substantially in parallel with the surface opposite to the ABS.
It is also preferred that the plurality of pairs of arm sections have different lengths with each other, and that both side ends of the one end section and the other end section are connected to the plurality of pairs of arm sections, respectively.
It is further preferred that the one end section of the vibration transfer member includes a plurality of end members separated with each other, and that both ends of the end member are connected to ends of the plurality of pairs of arm sections.
It is further preferred that the at least one head element is at least one thin-film magnetic head element.
According to the present invention, furthermore, an HGA includes a head slider provided with at least one head element, a support member including a suspension and having a plurality of resonance frequencies, and a vibration transfer member of a plane shape inserted between the suspension and the head slider to which vibrations are applied from the support member. The vibration transfer member has a plurality of resonance frequencies equal to or near the plurality of resonance frequencies of the support member. The vibration transfer member has a plurality of pairs of arm sections for coupling a rear end section of the vibration transfer member with a top end section of the vibration transfer member. The rear end section of the vibration transfer member is fixed to the suspension and the top end section of the vibration transfer member is fixed to the head slider so that apparent vibrations of the head slider are substantially canceled by resonances of the vibration transfer member.
When the suspension (load beam) resonates at a plurality of resonance frequencies, the vibration transfer member also resonates at a plurality of resonance frequencies. The rear end section of the vibration transfer member vibrates in phase with the flexure but the top end section of the vibration transfer member vibrates in substantially inverted phase or deviated phase as the flexure. Therefore, the vibration transfer member operates so as to move a position of the head slider back to its original position that will be positioned when no resonance occurs, resulting the apparent vibrations of the head slider to cancel.
As aforementioned, according to the present invention, only by additionally attaching the vibration transfer member with a simple structure, the mechanical vibrations can be extremely effectively canceled without greatly changing a conventional structure of the HGA. Also, since a configuration of a servo circuit of the actuator can be simplified, a manufacturing cost of the magnetic disk drive apparatus can be reduced.
Also, since the vibration transfer member is configured in a plane shape, no bending process is needed and its characteristics can be adjusted only by executing a photo-etching process. Thus, a fabrication of the vibration transfer member can become very easy and also extremely high precision can be expected. The latter will present the minimum variation in the characteristics caused by a dimensional error.
Particularly, according to the present invention, because the vibration transfer member has a plurality of pairs of arm sections for coupling one end section of the vibration transfer member with the other end section of the vibration transfer member so as to vibrates at a plurality of resonance frequencies that are equal to or near the plurality of resonance frequencies of the vibration-origination system, vibrations due to these plurality of resonance frequencies applied to the object can be simultaneously and effectively suppressed.
It is preferred that the HGA further includes first damper layers provided between the top end section of the vibration transfer member and the suspension, for attenuating the vibration of the head slider. To the both surfaces of the first damper layers, vibrations of substantially inverted phase or deviated phase with each other are applied from the flexure and the vibration transfer member, respectively. Thus the first damper layers operate to restrict an excessive inverse-movement of the vibration transfer member so as to attenuate the amplitude of the vibrations, and therefore the vibrations of the head slider fixed to the top end section of the vibration transfer member are attenuated.
It is preferred that the HGA further includes a second damper layer provided between the rear end section of the vibration transfer member and the head slider, for attenuating the vibration of the head slider.
It is also preferred that the first and/or second damper layers are formed by a flexible resin adhesive adhered to the vibration transfer member and to the suspension.
It is further preferred that the HGA is configured to apply a load in an up-and-down direction to the first and/or second damper layers. In the actual HGA, a load from the suspension is applied to the vibration transfer member and a resistance force from the recoding disk is applied to the head slider. Thus, forces in up-and-down directions are applied to the damper layers, and therefore the damping effect of the damping layers increases. The resonance frequency of a system consisting of the vibration transfer member and the damper layers varies depending upon a level of the applied load.
It is preferred that the head slider is fixed to one surface of the vibration transfer member and the suspension is fixed to the other surface of the vibration transfer member. Since the first damper layers are provided between the top end section of the vibration transfer member and the suspension, a gap space for inserting an adhesive can be automatically obtained between the vibration transfer member and the suspension. This results extremely easy assembling of the vibration transfer with the suspension. Also, if the second damper layer is provided between the rear end section of the vibration transfer member and the head slider, a gap space for inserting an adhesive can be automatically obtained between the vibration transfer member and the head slider. This results extremely easy assembling of the vibration transfer member with the head slider.
It is preferred that the head slider has a surface opposite to its ABS, and that the vibration transfer member consists of a plane metal plate substantially in parallel with the surface opposite to the ABS.
It is also preferred that the plurality of pairs of arm sections have different lengths with each other, and that both side ends of the rear end section and the top end section are connected to the plurality of pairs of arm sections, respectively.
It is further preferred that the top end section of the vibration transfer member includes a plurality of end members separated with each other, and that both ends of the end members are connected to ends of the plurality of pairs of arm sections.
It is still further preferred that the at least one head element is at least one thin-film magnetic head element.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.